Improvement in safe ty-valves



1.6. HDDGINS.

l Safety-Valves.

N0.l5l,027, Patented May 19,1874.

JOHN COBOURG HODGINS, `OF TORONTO, CANADA.

saeaovsmsar iN SAFETY-VALVES.

Specification forming part of Letters Patent No. 151,027, dated May 19, 1574; application filed December 22, 1873.

To all whom it may concern:

Be it known that I, JOHN OOBOURG HODG- INS, of the city of Toronto, county of York, lrovince of Ontario, Canada, have invented a Lock-Up Safety-Valve, of which the following is a specification:

My invention relates to certain new and usefulimprovements in loeleup safety-valves for steam-boilers; and consists, first, in the peculiar formation ofthe valve and valve-seat, by which the valve, when closed, presents a smaller area to the action of the steam in the boiler than when it has been opened by the said action or pressure of steam, thereby requiring less power to hold the valve closed 5 but at the same time, when the valve is once ra-ised and the steam escaping, (the surface being increascd,) the valve is still further an( more completely opened.

Reference being had to the accompanying drawings, and to the letters of reference marked thereon, forming a part of this specification, Figure l is a sectional elevation, and Fi g. 2 is a sectional plan, of a` lock-up safety valve with my improvements embodied.

J is the upper plate of a boiler, to which is bolted the 4valve-seat casting B. A is the ported valve-seat, made of any suitable material, shaped and fitted into B, as shown. A1 is the valve, constructed to lit on the scat A, but also havin g an outer annular angular pro `jectin g lip, a, which iits into a similarly-shaped recess cut in B. The angular faces on the' valve A1 do not come quite in contact with the angular faces of I) cut on B, the steamjoint being made on the flat annular surfaces a of A, and c of A1. ln the center of the seat A a hole is drilled to within a short distance of its under surface, to receive a projectingteat, A3, either cast or fastened to the valve A1. To the valve A1 is also cast or attached the spindle A1, passing upward `and within the spiral spring C, and fitting into a suitable hole Vbored through the compression-screw E. The

spring O is contained within an outer casing, c, resting directly on the valve A1, and having a cup-shaped washer, c1, on top, fitting within the casing c. Between c1and the point of the compression-screw two washers are fitted on the spindle A2, the lower one, D, being a diaphragm of india-rubber, or other suitable material, the upper 011e, c2, having the corners of its lower edge rounded, the object being to cause the rubber, which is cut larger in diameter than the casing c, to press against the sides of the casing when the spring C is under compression, making a close joint, and preventing steam or air getting to the spring' C. B1 is that part of the outer shell or casing of the valve in which is cnt the nut for the compression-screw E. On its upper surface is an annular projection, also with a thread cut upon it to receive the upper cap B1. d d are anges on B1 and B2, through each of which a hole is drilled, the flanges being fastened together, as shown, by an ordinary padlock, H. In the upper end of the spindle A2 a parallel hole is sunk, in which the head f of the rod F works freely up and down, the mouth being` closed with an ordinary gland-screw, E. G is a lever, so placed and connected that it will raise the valve A1, but cannot put any additional pressure thereon.

On reference to the drawings it will be no ticed that by the formation of the valve-seat A only a small portion of the valve A1, when closed, is exposed to the pressure of the steam which reaches it through the ports c; but when once the pressure reaches the calculated resistance of the spring C, the valve A1 lifts.

In the common valves, the opening remains nearly uniform, and if the steam-pressure is increased, the lift of the valve is not in accordance with the increase of pressure, and in no case is it proportionate to the full area ofthe valve. The defective lifting of the valve is found to arisc'from a partial vacuum produced underneath it by the radiating discharge of the steam, forming an inverted cone, the center of which is kept in a state of exhaustion by the rapidly-escaping steam.

It will be readily seen that the steam in escaping from my safety-valve is deflected b y striking against the angular face of a, causing it to act against the angular projection b on the valve-seat casting B, from which it reacts on the outer angular surface of the valve A1, thereby having sufficient power to overcome all resistance in lifting the valve A1 to a height from the annular surface a equal to the area of the ports invalve-scat A, relieving the boiler instantaneously, while so soon as the velocity has abated, the pressure is correspondingly reduced, and the valve A closes at once. The top and bottom spindles A2 and A3 are made very free in their guides, as the angular faces a and b Will always insure the valve rcseating itself correctly, and insure the free action of the valve. All the couplings and moving parts being made free its, and bein g so thoroughly protected from the action of the steam, al1 tendency to stick is obviated, and instant action of the valve, when the steam arrives at the required pressure, is insured.

By some slight alterations this valve can also be used on the lever principle, or on the combined principle of both lever and spring.

valve-seat A, and also having an annular projection, a, fitting into the recess cut in B, arranged substantially as and for the purpose specified.

J. C. HODGINS.

Witnesses Guo. A. Arun, HUGH AIRD.

having a flat annular face, a, fitting on the` 

